• 디지털융복합연구
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• 제13권11호
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• pp.85-97
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• 2015

본 연구에서는 조직 내에 스며든 웹 기술이 얼마나 해당 조직에 융합되어 정보시스템의 성공에 이바지하는지 알아보고자 수행되었다. 위계적 회귀분석 등을 통해 확인한 연구 결과는 다음과 같다. 첫째, 최고 경영진 지원, 전략적 투자 정당성, 그리고 컴퓨터 접근과 사용은 웹 기술 융합에 긍정적인 영향을 미치고 있었다. 또한 웹 기술 융합은 정보시스템 프로젝트의 성공에 유의한 영향을 가지고 있음도 확인하였다. 둘째, 웹 기술 융합을 전략 차원과 활동 차원으로 구분하여 확인한 결과 전략 차원에서는 최고 경영진 지원이 정보시스템 성공에 가장 큰 영향력을 가진 반면 활동 차원에서는 전략적 투자 정당성이 제일 중요한 영향을 미치고 있었다. 셋째, 정보시스템 프로젝트의 성공에 영향을 미치는 웹 기술 융합에 있어서 세부 차원 중 전략 차원이 활동 차원보다 높은 성공요인임을 알 수 있었다. 따라서 웹 기술과 같은 정보기술은 조직의 성공을 위한 강력한 사업도구이며 높은 수익의 원천이 될 것이다.

• 한국대기환경학회지
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• 제20권5호
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• pp.633-645
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• 2004

A critical component of air pollution modeling is the representation of meteorological fields within a model domain, since an accurate air quality simulation requires an accurate portrayal of the three-dimensional wind fields. The present study investigated data assimilation using surface observational data in the complex coastal regions to simulate an accurate meteorological fields. Surface observational data were categorized into three groups(Near coastal region, Far coastal regiln 1, Far costal region 2) by the locations where the data are. Experiments were designed and MM5 was used in each case of regions. Case 1 is an experiment without data assimilation, Case N is executed with data assimilation using observational data by meteorological stations and AWS data located in the near coastal region, within 1 km. Case F1 is also an experiment with data assimilation using observational data by meteorological stations and AWS data located in the far coastal regiln 1, more than 1km and less than 5km from the coastal lines. Case F2 is appled to data assimilation using observational data by meteorological stations and AWS data located in the far coastal region 2, beyond 5km from the coastal lines. The result of this study indicated that data assimilation using data in the far coastal region 1 and 2 provided an attractive method for generating accurate meteorological fields, especially in the complex coastal regions.

• The Korean Journal of Ecology
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• 제16권3호
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• pp.261-273
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• 1993

The nitrogen assimilation rate of nitrogenous nutrients by reservior phytoplankton was masured in the in situ condition in the euphotic layer of Lakes Soyang, Chuncheon and Uiam located on the upper reaches of the North Han River System in August, 1983, Korea. The assimilation rate of ammonia, nitrate and urea nitrogen in surface water was 13, 2 and $13{\mu}g$ at. $N{\cdot}m^{-3}{\cdot}(12:10~18:15)^{-1}$ in Lake Soyang, 325, 27 and $59{\mu}g$ at. $N{\cdot}m^{-3}{\cdot}(12:30~18:30)^{-1}$ in Lake Chuncheon, and 174, 12 and $45{\mu}g$ at. $N{\cdot}m^{-3}{\cdot}(12:30~19:30)^{-1}$ in Lake Uiam. Ammonia and urea were perferntially utilized by reservoir phytoplankton. The dark/light ratios of nitrate assimilation were much lower than those of ammonia and urea assimilation of nitrate showed little contribution. The primary productuin was estimated as 59mg $C{\cdot}m^{-2}{\cdot}day^{-1}$ and 6.9mg $N{\cdot}m^{-2}{\cdot}day^{-1}$ in Lake Spyang, 217mg C{\cdot}m^{-2}{\cdot}day^{-1}$ and 26mg N{\cdot}m^{-2}{\cdot}day^{-1}$ in Lake Chuncheon, and 110mg C{\cdot}m^{-2}{\cdot}day^{-1}$ and 13mg N{\cdot}m^{-2}{\cdot}day^{-1}$ in Lake Uiam, with production ratios of 8.6, 8.4 and 8,4, respectively. The turnover time o ammonia and urea in the upper euphotic layer was 2 to 47 days and 4 to 38 days, respectively. Nitrate required much longer periods. In the euphotic layer of reservoirs, ammonia and urea played signigicant roles in the biogeoKDICical nitrogen metabolism.

• 한국환경과학회지
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• 제15권1호
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• pp.9-19
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• 2006

The purpose of this research is development of radar data assimilation observed at Jindo S-band radar The accurate observational data assimilation system is one of the important factors to meteorological numerical prediction of the region scale. Diagnostic analysis system LAPS(Local Analysis and Prediction System) developed by US FSL(Forecast Systems Laboratory) is adopted assimilation system of the Honam district forecasting system. The LAPS system was adjusted in calculation environment in the Honam district. And the improvement in the predictability by the application of the LAPS system was confirmed by the experiment applied to Honam district local severe rain case of generating 22 July 2003. The results are as follows: 1) Precipitation amounts of Gwangju is strong associated with the strong in lower level from analysis of aerological data. This indicated the circulation field especially, 850hPa layer, acts important role to precipitation in Homan area. 2) Wind in coastal area tends to be stronger than inland area and radar data show the strong wind in conversions zone around front. 3) Radar data assimilation make the precipitation area be extended and maximum amount of precipitation be smaller. 4) In respect to contribution rate of different height wind field on precipitation variation, radar data assimilation of upper level is smaller than that of lower level.

• 한국지구과학회지
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• 제33권4호
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• pp.309-319
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• 2012

연안 해상 바람 자원 평가에 적용되는 해상풍 위성자료 동화특성을 평가하기 위하여 수치실험을 실시하였다. 사용된 위성자료는 미항공우주국의 QuikSCAT과 유럽우주국의 ASCAT이다. 해상풍 위성자료 동화과정은 연안지역 바람 자원 평가의 정확성을 향상시키는 주요한 요소의 하나이다. QuikSCAT의 관측 가능한 빔폭이 상대적으로 넓기 때문에 QuikSCAT 해상풍 자료를 동화하여 제시된 연안 바람장이 ASCAT를 사용한 바람장보다 약간 높은 정확도를 제시한다. 그러나 센서의 직하 부근의 바람장은 상대적으로 ASCAT의 예측 정확도가 높게 나타난다. 이러한 해상풍 위성자료의 동화효과는 6시간 정도 지속되기 때문에 정확한 연안지역 바람장을 평가하기 위해서는 센서의 공간해상도뿐 아니라 시간해상도가 높은 해상풍 위성자료 동화 과정이 필요하다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.39-39
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• 2012

Data assimilation techniques have received growing attention due to their capability to improve prediction in various areas. Despite of their potentials, applicable software frameworks to probabilistic approaches and data assimilation are still limited because the most of hydrologic modelling software are based on a deterministic approach. In this study, we developed a hydrological modelling framework for sequential data assimilation, namely MPI-OHyMoS. MPI-OHyMoS allows user to develop his/her own element models and to easily build a total simulation system model for hydrological simulations. Unlike process-based modelling framework, this software framework benefits from its object-oriented feature to flexibly represent hydrological processes without any change of the main library. In this software framework, sequential data assimilation based on the particle filters is available for any hydrologic models considering various sources of uncertainty originated from input forcing, parameters and observations. The particle filters are a Bayesian learning process in which the propagation of all uncertainties is carried out by a suitable selection of randomly generated particles without any assumptions about the nature of the distributions. In MPI-OHyMoS, ensemble simulations are parallelized, which can take advantage of high performance computing (HPC) system. We applied this software framework for several catchments in Japan using a distributed hydrologic model. Uncertainty of model parameters and radar rainfall estimates is assessed simultaneously in sequential data assimilation.

• 대한음성학회:학술대회논문집
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• 대한음성학회 1996년도 10월 학술대회지
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• pp.514-514
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• 1996

Igbo, a new Benue Congo language has a vowel harmony system which, like that of Akan, is based on the pharynx size or tongue root position. In this study we examine Igbo vowel harmony with particular reference to assimilatory patterns of vowels in different harmony sets. This is to gain some insight into the factors involved in Igbo vowel assimilation, and to establish to what extent reports on Akan vowel assimilation are validated in Igbo. Tokens of the eight phonemic vowels of Standard Igbo are recorded from three native speakers of Igbo. The vowels are acoustically investigated (using the LPC analysis of CSL) in individual lexical items and within carefully designed carrier phrases. The F1 and F2 values of the vowels are obtained as these formant values are generally useful in establishing the salient characteristics of vowels. Vowels from the harmony sets are juxtaposed in the carrier phrases to ascertain the extent of assimilation. Results of the investigation show that the F1 values, to a large extend, are enough to characterize these vowels. The (-Expanded) vowels have higher F1 values than their (+Expanded) counterpart. Where there is an overlap in F1 values for some vowels the F1 bandwidth values serve to distinguish between the vowels. The overlap often reported in Akan for /I/ and /e/ on the one hand and /${\mho}$/ and /o/ on the other is not validated in Igbo. While the F1 values for these pairs of vowels are quite similar for one of our speakers, there is an appreciable difference between the F1 values of these vowels for the other two speakers. There is however an overlap for /e/ and /o/ for one of the speakers. Assimilations are generally regressive across word boundaries. It is, however, necessary to point out that the general perceptual impression that one of the vowels completely assimilates to the other, is not borne out by our investigation. Most of our F1 and F2 values for the vowels in individual lexical items are altered in assimilations. This then suggests that assimilation involving these vowels is partial rather than complete. The emerging 'allophones' are acoustically similar to the (+Expanded) vowel involved in the assimilation, that is when vowels from different harmony sets are involved. We conclude that while assimilation of Igbo vowels involves some phonological considerations, phonetic factors appear to be permanent in deciding the final form of the vowels.

• 대기
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• 제17권1호
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• pp.1-15
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• 2007

A constraint based on climatology is introduced to the cost function of the three-dimensional variational assimilation (3dVar) to correct the error of the zonal mean wind structure in the global data assimilation system at Korea Meteorological Administration (KMA). The revised cost function compels the analysis fit to the chosen climatology while keeping the balance between the variables in the course of analysis. The constraint varies selectively with the vertical level and the horizontal scale of the motion. The zonally averaged wind field from European Centre for Medium-Range Weather Forecasts Re-Analysis 40 (ERA-40) is used as a climatology field in the constraint. The constraint controls only the zonally averaged stratospheric long waves with total wave number less than 20 to fix the error of the large scale wind field in the stratosphere. The constrained 3dVar successfully suppresses the erroneous westerly in the stratospheric analysis promptly, and has been applied on the operational global 3dVar system at KMA.

• 한국대기환경학회지
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• 제23권5호
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• pp.585-595
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• 2007

Representative impacts and effectiveness of surface meteorological observation data assimilation were examined in order to use wind resources estimation around southern coastal area of the Korean Peninsula. The data used in study are observational wind and temperature data at 5 and 41 sites of Regional Meteorological Offices and Automatical Weather Systems, respectively. Observation wind speed data tends to show small effective radius with limited area. Especially assimilation impacts of data observed at peninsula type sites like Yeosu play only around the inside of the peninsula. This limited effective radius for wind speed is caused by the strong correlation between topography and wind speed. And the efficient radius for surface air temperature is larger than that of wind. Data assimilation for observational air temperature is useful to increase the accuracy of wind energy estimation. However assimilation of wind data requires special care in its application due to high sensitivity of topographical complexity.

• 대기
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• 제28권2호
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• pp.141-151
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• 2018

The KIAPS global model and data assimilation system were extended to assimilate brightness temperature from the Sondeur $Atmosph{\acute{e}}rique$ du Profil $d^{\prime}Humidit{\acute{e}}$ Intertropicale par $Radiom{\acute{e}}trie$ (SAPHIR) passive microwave water vapor sounder on board the Megha-Tropiques satellite. Quality control procedures were developed to assess the SAPHIR data quality for assimilating clear-sky observations over the ocean, and to characterize observation biases and errors. In the global cycle, additional assimilation of SAPHIR observation shows globally significant benefits for 1.5% reduction of the humidity root-mean-square difference (RMSD) against European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) analysis. The positive forecast impacts for the humidity and temperature in the experiment assimilating SAPHIR were predominant at later lead times between 96- and 168-hour. Even though its spatial coverage is confined to lower latitudes of $30^{\circ}S-30^{\circ}N$ and the observable variable is humidity, the assimilation of SAPHIR has a positive impact on the other variables over the mid-latitude domain. Verification showed a 3% reduction of the humidity RMSD with assimilating SAPHIR, and moreover temperature, zonal wind and surface pressure RMSDs were reduced up to 3%, 5% and 7% near the tropical and mid-latitude regions, respectively.